JP2012189044A - Laser ignition device and control method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laser ignition device having excellent mountability on an engine and excellent reliability and safety, and to provide a control method of the laser ignition device.SOLUTION: The laser ignition device 100b includes as a laser output detecting means 3b, an optical element 30b refracting an advance direction of the returned light REFof a pulse laser LSRemitted from a laser oscillator 41 and a returned light detecting sensor 31 detecting the pulse laser returned light REFrefracted by the optical element 30b, and includes, as an excited light source deterioration detecting means 3b, an optical element 30b refracting a partial advance direction of an excited laser LSRemitted from a semiconductor laser 2 provided as an excited light source and an excited light detecting sensor 33 detecting a partial REFof the excited laser LSRrefracted by the optical element 30b.

Description

  The present invention relates to a laser ignition device used for ignition of an internal combustion engine mounted in a limited mounting space such as a vehicle and a control method thereof.

  In recent years, a Q-switch type laser medium is irradiated with an excitation light source such as a flash lamp or a semiconductor laser to oscillate a pulse laser that emits energy with a short pulse width and concentrates it. Various laser devices have been proposed that ignite an internal combustion engine or process a metal by concentrating using a system component and concentrating high energy.

  For example, Patent Document 1 discloses that a laser device that can adjust the power and pulse width of a laser pulse to be output and that outputs a laser pulse toward fuel in a combustion chamber of an internal combustion engine, and the combustion chamber at an ignition timing. After a first pulse laser having a peak power capable of generating a plasma is output from the laser device, a second laser pulse having a peak power lower than the first laser pulse is generated from the laser device in the combustion chamber. A laser ignition device is disclosed that includes a control device that controls the laser device so that the laser device is output toward the.

  Further, in Patent Document 2, as a method for correcting the output of a laser oscillator, a current signal I (n) input to an input current driving circuit for driving an excitation lamp is converted into a reference light amount value Ls (n) and a laser output light amount value Lb ( n), an amount ΔP (n) corresponding to the difference from n), an amount ΔJ (n) corresponding to the difference between the integrated reference light amount value ΣLb (n) and the integrated laser output light amount value ΣLs (n), and a predetermined shape A method of matching the laser output with the reference waveform by calculating based on the reference current value Is (n + 1) is disclosed.

However, in the conventional laser ignition device as disclosed in Patent Document 1, when the laser oscillator is mounted in a limited mounting space of the engine head, it is difficult to sufficiently cool, and the ambient temperature changes. Largely, the pulse interval of the oscillated laser changes due to temperature change or deterioration of the laser oscillator, and there is a possibility that the ignition timing cannot be controlled to an appropriate value.
In addition, in the conventional laser ignition device, in consideration of the mountability, when only an optical system component such as a condenser lens is mounted on the engine head and the laser oscillation device is provided outside the engine head, Both the oscillator and the optical system components are connected via a transmission means such as an optical fiber, but it is necessary to reliably detect the connection state of the optical fiber in order to ensure the safety of the vehicle driver. There is.

On the other hand, in a laser processing apparatus such as that disclosed in Patent Document 2, the laser oscillator is placed in an environment that can be sufficiently cooled by a water-cooling apparatus or the like. In order to satisfy the application as a device, if the energy amount of the laser output matches the reference waveform, there is no problem with the pulse interval and the number of pulses oscillated from the laser oscillator. It is not the structure which considered the problem in.
Further, in the conventional laser oscillator correction method as disclosed in Patent Document 2, a part of the light actually emitted from the laser oscillator is branched by a beam splitter, detected by an optical sensor, and used for correcting the laser output. However, it is difficult to provide such a branching means in a limited mounting space of the engine head.
In addition, when the output correction is performed by branching a part of the high energy pulse laser oscillated from the laser oscillator and detecting it using the optical sensor as in the past, the optical sensor deteriorates quickly. There is a risk of becoming.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a laser ignition device that is small in size, excellent in mountability on an engine, and excellent in reliability and safety, and a control method thereof.

  According to the first aspect of the present invention, a driving current for driving the excitation light source is applied in accordance with an ignition signal provided in accordance with the operating state of the engine from an electronic control device that is provided in the internal combustion engine and controls the engine. In the laser ignition device that oscillates the excitation laser emitted from the laser as a pulse laser having a high energy density by a laser oscillator, further increases the energy density by the condensing means and ignites the mixture in the combustion chamber, as a laser output detection means, An optical element that refracts the traveling direction of the return light of the pulse laser oscillated from the laser oscillator, and a return light detection sensor that detects the return light of the pulse laser refracted by the optical element.

  According to the second aspect of the present invention, a driving current for driving the excitation light source is applied in accordance with an ignition signal provided in the internal combustion engine and transmitted in accordance with the operating condition of the engine from an electronic control device that controls the engine, and the excitation light source As a pumping light source deterioration detecting means in a laser igniter that oscillates an excitation laser emitted from a laser as a pulse laser having a high energy density by a laser oscillator and further increases the energy density by a condensing means to ignite an air-fuel mixture in a combustion chamber An optical element that refracts the traveling direction of a part of the excitation laser emitted from the excitation light source, and an excitation light detection sensor that detects a part of the excitation laser refracted by the optical element.

  According to a third aspect of the present invention, a drive current for driving an excitation light source is applied in accordance with an ignition signal provided in an internal combustion engine and transmitted from an electronic control device that controls the engine in accordance with an operation state of the engine, and the excitation light source In the laser ignition device that oscillates the excitation laser emitted from the laser as a pulse laser having a high energy density by a laser oscillator and raises the energy density by the condensing means to ignite the air-fuel mixture in the combustion chamber, An excitation light source deterioration detecting means comprising: an optical element that refracts the traveling direction of the return light of the pulse laser oscillated from the laser oscillator; and a return light detection sensor that detects the return light of the pulse laser refracted by the optical element. An optical element that refracts a part of the traveling direction of the excitation laser emitted from the excitation light source, and the optical element Comprising an excitation light sensor for detecting a portion of the folded excitation laser.

  According to a fourth aspect of the present invention, a driving current for driving an excitation light source is applied in accordance with an ignition signal provided in an internal combustion engine and transmitted from an electronic control device for controlling the engine in accordance with the operating state of the engine, A control method of a laser ignition device that oscillates an excitation laser emitted from a laser as a pulse laser having a high energy density by a laser oscillator, further increases the energy density by a condenser lens, and ignites an air-fuel mixture in a combustion chamber. As output detection means, an optical element that refracts the traveling direction of the return light of the pulse laser oscillated from the laser oscillator, and a return light detection sensor that detects the return light of the pulse laser refracted by the optical element, The actual number of output pulses detected based on the output of the return light detection sensor is one ignition signal transmitted from the electronic control unit. When less than the target number of pulses of the pulse laser should be oscillated from the laser oscillator for items, a longer application time of the driving current, or, to increase the driving current.

  According to the invention of claim 5, a drive current for driving the excitation light source is applied in accordance with an ignition signal provided in the internal combustion engine and transmitted from an electronic control device for controlling the engine according to the operating state of the engine, and the excitation light source A method of controlling a laser ignition device that oscillates an excitation laser emitted from a laser as a pulse laser having a high energy density by a laser oscillator, further increases the energy density by a condenser lens, and ignites an air-fuel mixture in a combustion chamber. As a light source deterioration detecting means, an optical element that refracts the traveling direction of a part of the excitation laser emitted from the excitation light source and an excitation light detection sensor that detects a part of the excitation laser refracted by the optical element are provided. The peak voltage of the output detected by the excitation light detection sensor was previously detected by the excitation light detection sensor in the initial state. When lower than the peak voltage initial value of the force, a longer application time of the driving current, or, to increase the driving current.

  According to a sixth aspect of the present invention, a driving current for driving the excitation light source is applied in accordance with an ignition signal provided in the internal combustion engine and transmitted in accordance with the operating state of the engine from an electronic control device that controls the engine, and the excitation light source A control method of a laser ignition device that oscillates an excitation laser emitted from a laser as a pulse laser having a high energy density by a laser oscillator, further increases the energy density by a condenser lens, and ignites an air-fuel mixture in a combustion chamber. As an oscillator deterioration detection means, an optical element that refracts the traveling direction of the return light of the pulse laser oscillated from the laser oscillator and a return light detection sensor that detects the return light of the pulse laser refracted by the optical element are provided. The actual number of output pulses detected based on the output of the return light detection sensor is transmitted from the electronic control unit. When the number of pulse pulses to be oscillated from the laser oscillator with respect to the ignition signal is less than the target pulse number, the drive current application time is lengthened, or the drive current is increased and then the number of output pulses detected again is When the number is less than the target number of pulses, it is determined that the laser oscillator has deteriorated.

  According to a seventh aspect of the present invention, a driving current for driving an excitation light source is applied in accordance with an ignition signal provided in an internal combustion engine and transmitted from an electronic control device for controlling the engine in accordance with an operation state of the engine, A control method of a laser ignition device that oscillates an excitation laser emitted from a laser as a pulse laser having a high energy density by a laser oscillator, further increases the energy density by a condenser lens, and ignites an air-fuel mixture in a combustion chamber. As an oscillator deterioration detection means, an optical element that refracts the traveling direction of the return light of the pulse laser oscillated from the laser oscillator and a return light detection sensor that detects the return light of the pulse laser refracted by the optical element are provided. The output of the return light detection sensor is not more than a predetermined threshold even though the excitation laser is output from the excitation light source. Sometimes, it is determined that the excitation light source and the said laser oscillator is not connected, to stop the oscillation of the excitation laser from said pumping light source.

  According to an eighth aspect of the present invention, a driving current for driving an excitation light source is applied in accordance with an ignition signal provided in an internal combustion engine and transmitted from an electronic control device for controlling the engine according to the operating state of the engine, A method of controlling a laser ignition device that oscillates an excitation laser emitted from a laser as a pulse laser having a high energy density by a laser oscillator, further increases the energy density by a condenser lens, and ignites an air-fuel mixture in a combustion chamber. As a light source deterioration detecting means, an optical element that refracts the traveling direction of a part of the excitation laser emitted from the excitation light source and an excitation light detection sensor that detects a part of the excitation laser refracted by the optical element are provided. The peak voltage of the output detected by the excitation light detection sensor and the detection by the excitation light detection sensor in the initial state in advance When the difference between the peak voltage initial value of the force exceeds a predetermined threshold value, it is determined that the degradation of the excitation light source.

According to the first aspect of the present invention, it is possible to detect the state of the laser oscillator based on the output of the return light detection sensor, and the oscillation interval of the pulse laser actually oscillated varies due to the temperature change of the laser oscillator. It is sometimes possible to make corrections so as to match the target oscillation interval.
Further, unlike the prior art, the pulsed laser having a high energy density oscillated from the laser oscillator itself is not detected by spectroscopy, but the return light having a low energy density is detected. Durability is improved and downsizing is easy.

According to the invention of claim 2, it is possible to detect the deterioration state of the excitation light source based on the output of the excitation light detection sensor, and the drive current for driving the excitation light source is corrected according to the deterioration state of the excitation light source. Thus, the output of the excitation light emitted from the excitation light source can be stabilized.
Further, since a part of the excitation laser having a lower energy density than that of the pulse laser is detected, the optical system is hardly deteriorated, durability is improved, and miniaturization is easy.

According to the invention of claim 3, the effects of the invention of claim 1 and the effect of the invention of claim 2 can be obtained in a superimposed manner, and more stable pulse laser oscillation can be achieved. improves.
In addition, from the difference between the output of the return light detection sensor and the output of the excitation light detection sensor, the presence of leakage of excitation light is detected between the excitation light source and the laser oscillator, and the internal combustion engine is operated. It is also possible to ensure the safety of the driver.

  According to the invention of claim 4, when the oscillation interval of the output pulse laser becomes longer due to the temperature rise of the laser oscillator, it becomes possible to make it coincide with the target oscillation interval, and the operating condition of the internal combustion engine Appropriate ignition according to is realized.

  According to the invention of claim 5, when the output of the excitation light is reduced due to the deterioration of the excitation light source, the output of the excitation light can be stabilized, and the appropriate ignition according to the operating condition of the internal combustion engine can be performed. Realized.

  According to the sixth aspect of the invention, it is possible to promptly detect an abnormality of the laser oscillator and prompt replacement thereof, thereby ensuring reliability as an ignition device.

  According to the seventh aspect of the present invention, when the connection between the excitation light source and the laser oscillator is disconnected, it is possible to reliably prevent the leakage of laser light to the outside, and to ensure the safety of the driver. Reliability and safety as a device are ensured.

  According to the invention of claim 8, it is possible to promptly detect an abnormality of the history light source and prompt the replacement, and the reliability as the ignition device is ensured.

Sectional drawing which shows the outline | summary of the laser ignition apparatus in the 1st Embodiment of this invention. Sectional drawing which shows the outline | summary of the laser ignition apparatus in the 2nd Embodiment of this invention. Sectional drawing which shows the outline | summary of the laser ignition apparatus in the 3rd Embodiment of this invention. Sectional drawing of the laser oscillation apparatus used for the laser ignition apparatus in the 4th Embodiment of this invention. The outline | summary of the laser ignition apparatus in the 5th Embodiment of this invention is shown, (a) is sectional drawing of the whole, (b) is sectional drawing which shows a heat sink part. The time chart which shows the control method used for the laser ignition device of this invention. The time chart which shows the other control method used for the laser ignition device of this invention.

  The laser ignition device of the present invention detects either one or both of the return light of the pulse laser and / or the pump laser in response to fluctuations in the oscillation period of the pulse laser caused by the temperature change of the laser medium or the deterioration of the semiconductor laser. Then, the oscillation period of the actually oscillated pulse laser is detected and corrected so that the number of pulses suitable for the combustion condition or the laser output is obtained, so that the high supercharged engine, the high compression engine, the lean mixture engine Thus, it is intended to realize stable ignition in a difficult-ignition internal combustion engine.

With reference to FIG. 1, the outline | summary of the laser ignition apparatus 100 in the 1st Embodiment of this invention is demonstrated. In the present invention, the internal combustion engine to be applied is not limited, but as shown in the figure, the internal combustion engine 7, the cylinder head 70, the intake cylinder 71, the intake valve 711, the exhaust cylinder 72, the exhaust valve 722, A combustion chamber 73 is defined by a cylinder block and a piston (not shown). The tip of the laser spark plug 4 fixed to the cylinder head 70 is opposed to the combustion chamber 73, and a pulse is generated in the air-fuel mixture introduced into the combustion chamber 73. The laser is focused to ignite the air-fuel mixture.
The laser ignition device 100 in the present embodiment detects the return light REF _PLS of the pulsed laser LSR _PLS oscillated from the laser oscillator 41 and feeds it back to the control of the drive current applied to the semiconductor laser 1, so that the temperature of the laser oscillator 41 It is characterized in that stable ignition of the internal combustion engine can be realized by correcting the increase / decrease in the output pulse interval and the increase / decrease in the number of output pulses due to the change.

The laser ignition device 100 includes a semiconductor laser 1 provided as an excitation light source, a drive circuit 2 for driving the semiconductor laser 1, laser output detection means 3 provided for detecting the state of the laser oscillator, and a cylinder of the internal combustion engine 8. The laser spark plug 4 mounted on the head 70, the output energy determining means 5, and an electronic control unit (ECU) 6 for controlling them are constituted.
The semiconductor laser 1 uses a laser diode formed of a crystal material such as GaAlAs or InGaAs, and emits an excitation laser LSR _PMP when a driving current (D ₁ or D _AMD ) is applied from the driving circuit 2.

The excitation laser LSR _PMP emitted from the semiconductor laser 1 is transmitted to the laser spark plug 4 via the optical fibers 10 and 35 and the laser output detection means 3.
In the present embodiment, the laser output detection means 3 includes a beam splitter 30 provided as an optical element that refracts the traveling direction of the pulsed laser return light REF _PLS , and the pulsed laser return light REF refracted by the beam splitter 30. It is comprised with the return light detection sensor 31 which detects _PLS .

Beam splitter 30 is made of quartz glass or the like, on the surface of the opposite side to the laser oscillator 41 of the optical element 300 formed in a substantially flat, the excitation laser _{LSR PMP} is transmitted, the pulse laser _{LSR PLS} return light _{REF PLS} Is a half mirror on which a reflecting partial reflection film 301 for reflection is formed, and is disposed at an angle of 45 ° with respect to the traveling direction of the excitation laser.
As the return light detection sensor 31, for example, a photodiode including a semiconductor element such as GaAs, Si, AlGaSb, InGaAs, GaAsN, or a phototransistor is used.
The pulse laser return light REF _PLS has a specific wavelength (for example, 1064 nm) and is the wavelength of the excitation laser LSR _PMP (for example, 808 nm). , Si, InGaAs), it is desirable to attach an optical filter or the like that cuts the wavelength (800 to 815 nm) of the excitation laser LSR _PMP to the incident surface of the light detection sensor 31.

The laser ignition plug 4 is coaxially arranged in a plug housing 45 formed in a substantially cylindrical shape, and includes an excitation light condensing optical system component 40, a laser oscillator 41, a beam expander 42, a condensing lens 43, and a protective cover. 44.
The laser oscillator 41 includes an excitation light transmission film 410 that transmits the excitation laser LSR _PMP from the incident surface, a fluorescent partial reflection film 411 that totally reflects light having a wavelength longer than the excitation light generated in the laser medium, and a laser medium. 412, the saturable absorber 413, and the partial reflection mirror 414 constitute a resonator.

Light having a wavelength longer than that of the excitation laser LSR _PMP generated in the laser medium 412 resonates and is amplified until the intrinsic threshold of the saturable absorber 413 is exceeded.
When the resonance-amplified laser light exceeds the threshold value, the saturable absorber 413 acts as a passive Q switch, and is instantaneously emitted as a pulse laser LSR _PLS having a high energy density.
At this time, part of the pulse laser LSR _PLS returns to the beam splitter 30 from the laser oscillator 41 via the optical fiber 35 as pulse laser return light REF _PLS .

The pulse laser return light REF _PLS is reflected by the return light partial reflection film 301 of the beam splitter 30 in the side surface direction orthogonal to the traveling direction of the pal laser return light REF _PLS , and further enters the return light detection sensor 31 provided in the traveling direction. Shine.
Return light detecting sensor 31, a pulse laser _LSR actually the number of pulses of the pulsed laser return light _{REF PLS} matching number of oscillation pulses output of _{PLS (PLS} 2), and / or proportional to the output of the pulse laser _{LSR PLS} The intensity of the pulse laser return light REF _PLS is detected, and a return light signal 30 is output.

The return light signal 30 output from the laser output detection unit 3 is input to the output energy determination unit 5.
The output energy determination unit 5, before the input of the return light signal 30, in accordance with the ignition signal IGt and control target value 60 of the target number of pulses PLS ₁ originating from ECU 6, a standard drive for driving the driving circuit 2 signal 50 is transmitted, standard driving current D ₁ from the drive circuit 2 at a timing corresponding to the ignition signal IGt is applied to the semiconductor laser 1.
Further, the output energy determining means 5 detects the state of the laser oscillator 41 from the difference between the input detection pulse number PLS ₂ and the target pulse number PLS ₁ after the return light signal 30 is input, and the corrected pulse number PLS. _In order to realize _AMD , the drive signal 50 for driving the drive circuit 2 is corrected and transmitted, and the corrected drive current D _AMD is applied to the semiconductor laser 1 from the drive circuit 2 at a timing according to the ignition signal IGt. The
By applying the drive current D ₁ or D _AMD from the drive circuit 2, the pump laser LSR _PMP corresponding to the state of the laser oscillator 41 is emitted from the semiconductor laser 1 to the laser oscillator 41. A specific method of correcting the corrected drive current D _AMD will be described later with reference to FIGS.

The pulse laser LSR _PLS oscillated from the laser oscillator 41 is adjusted by the beam expander 42 so as to be parallel light having a predetermined beam diameter.
The beam expander 42 includes a concave lens 420 that expands the beam diameter of the pulse laser LSR _PLS and a convex lens 421 that refracts the light so as to be parallel light.
The pulse laser LSR _PLS adjusted to parallel light by the beam expander 42 is placed at a condensing point FP disposed at a predetermined spatial position in the combustion chamber 83 of the combustion engine 8 by a condensing lens 43 provided as a condensing unit. The air-fuel mixture is condensed and further energized to ignite the air-fuel mixture introduced into the combustion chamber using a fuel injection device (not shown). The position of the condensing point FP can be appropriately changed according to the combustion characteristics of the internal combustion engine to be applied.

Furthermore, in the present embodiment, when the pumping laser LSR _PMP is output from the semiconductor laser 1 and the return light output signal 30 output from the return light detection sensor 31 is below a predetermined threshold, the semiconductor laser 1 It is determined that the path for transmitting the pump laser LSR _PMP is not connected such that the optical fiber 35 connecting the laser oscillator 41 and the laser oscillator 41 is disconnected, and the oscillation of the pump laser LSR _PMP is stopped.
The determination result may be used to stop the fuel injection and the start of the engine starter.

The ECU 6 sets, as the control target value 60, the target pulse of the pulse laser LSR _PLS oscillated from the laser oscillator 41 in response to the ignition signal IGt together with the ignition signal IGt that determines the ignition timing according to the operating state of the internal combustion engine 7. The number PLS ₁ is transmitted to the output energy determination means 5 as the control target value 60.

With reference to FIG. 2, the outline | summary of the laser ignition apparatus 100a in the 2nd Embodiment of this invention is demonstrated. The laser ignition device 100 in the above embodiment has been configured to detect the return light REF _PLS of the pulse laser LSR _PLS oscillated from the laser oscillator 41 and correct the fluctuation of the laser oscillator 41. As the pumping light source deterioration detecting means 3a, the reflected light REF _PMP of the pumping laser LSR _PMP is detected, the deterioration of the semiconductor laser 1 is detected, the output of the pumping laser LSR _PMP accompanying the deterioration of the semiconductor laser 1, and the cause thereof Thus, it is possible to realize stable ignition by correcting the output decrease of the pulse laser LSR _PLS oscillated from the laser oscillator 41.
In the following description, the same components as those in the above embodiment are denoted by the same reference numerals, and the description thereof will be omitted. The description will focus on the characteristic parts in each embodiment.

In the present embodiment, the excitation light source deterioration detection means 3a has a beam splitter 30a provided as an optical element that refracts a part of the excitation laser LSR _PMP and extracts it as excitation laser reflected light REF _PMP , and the traveling direction is determined by the beam splitter 30a. The excitation light detection sensor 33 detects the refracted excitation laser reflected light REF _PMP .

In the beam splitter 30a, an excitation laser partial reflection film 302 that reflects a part of the excitation laser LSR _PMP is formed on the surface of the optical element 300 made of quartz glass or the like on the side facing the semiconductor laser 1 of the optical element 300. The half mirror is disposed at an angle of 45 ° with respect to the traveling direction of the excitation laser LSR _PMP .
As the excitation light detection sensor 33, for example, a photodiode, a phototransistor, or the like including a semiconductor element such as GaAs, Si, AlGaSb, InGaAs, GaAsN, or the like is used. The excitation laser reflected light REF _PMP has a specific wavelength (for example, 808 nm) and is the wavelength of the pulsed laser return light REF _PLS (for example, 1064 nm). Therefore, a sensor that detects both wavelengths. (For example, when Si or InGaAs) is used, it is desirable to attach an optical filter or the like that cuts the wavelength (800 to 815 nm) of the excitation laser LSR _PMP to the incident surface of the light detection sensor 31.

Since the intensity of the excitation laser reflected light REF _PMP detected by the excitation light detection sensor 33 is proportional to the intensity of the excitation laser LSR _PMP , the degradation state of the semiconductor laser 1 can be detected by determining this as a threshold value. .
Further, by feeding back the correction of the drive current applied to the semiconductor laser 1 enter the peak voltage V ₁ of the output 34 of the excitation light detection sensor 33 to the energy output determination unit 5a, the output decreases due to deterioration of the semiconductor laser 1 Can be supplemented.

In the present embodiment, an output correction method performed by the energy output determination unit 5a and a method for determining the deterioration state of the semiconductor laser 1 will be described.
At a temperature of the semiconductor laser 1 is fixed condition, the output voltage V _IN and a predetermined threshold voltage of the excitation light reflected REF _PMP detected by the excitation light detection sensor 33 when the flow of predetermined drive currents D ₁ to the semiconductor laser 1 Degradation can be determined by comparing with V _REF .
For example, the peak value of the output voltage _VIN of the excitation light detection sensor 33 in the initial state is stored in advance in the ECU 6 as the peak voltage initial value V ₀ , and the peak value V of the output voltage of the excitation light detection sensor 33 when a predetermined time has elapsed. ₁ is compared with the peak voltage initial value V _0, and when the peak voltage difference (V ₁ −V ₀ ) is equal to or less than a predetermined threshold, the peak value V ₁ of the output voltage of the excitation light detection sensor 33 is the initial peak value. By determining the corrected drive signal D _AMD so as to increase the drive current applied to the semiconductor laser 1 so as to coincide with V ₀ , the excitation laser LSR _PMP emitted from the semiconductor laser 1 can be stabilized. It becomes possible.

Further, the learning of the peak voltage V ₁ is repeated, and when the supplied power exceeds a predetermined power source capacity or when the peak voltage difference (V ₁ −V ₀ ) exceeds a predetermined threshold value, the semiconductor laser 1 It is possible to determine the deterioration and store the fact that the state is in a deteriorated state as a self-diagnosis signal, or urge the driver to replace the semiconductor laser 1 by turning on a warning lamp.
The deterioration determination of the semiconductor laser 1 is preferably performed under a condition where the power is lower than the normal driving current and the pulse laser LSR _PLS is not oscillated from the laser oscillator 41, and the ignition signal IGt is not transmitted from the ECU 6. It is preferable to carry out the operation while the semiconductor laser 1 is stopped or while the temperature of the semiconductor laser 1 is constant.

With reference to FIG. 3, the outline | summary of the laser ignition apparatus 100b in the 3rd Embodiment of this invention is demonstrated.
The laser ignition device 100b in the present embodiment includes both the features of the laser ignition device 100 in the first embodiment and the features of the laser ignition device 100a in the second embodiment.
Therefore, according to the present embodiment, it is possible to suppress both the fluctuation of the pulse laser output accompanying the temperature change of the laser oscillator 41 and the fluctuation of the pulse laser output accompanying the deterioration of the semiconductor laser 1 and realize more stable ignition. .
In the present embodiment, the detection means 3b having both the laser output detection means and the excitation light source deterioration detection means refracts the traveling direction of the pulse laser return light REF _PLS and refracts a part of the excitation laser LSR _PMP for excitation. A beam splitter 30b provided as an optical element to be extracted as the laser reflected light REF _PMP , a return light detection sensor 31 for detecting the pulsed laser return light REF _PLS whose traveling direction is refracted by the beam splitter 30b, and a traveling direction by the beam splitter 30b And an excitation light detection sensor 33 for detecting the excitation laser reflected light REF _PMP that is refracted.

Further, the laser output determining means 5b in the present embodiment includes an ignition signal IGt oscillated from the ECU 6 according to the operating state of the internal combustion engine 7, a target pulse PLS _1, and an output 32 (PLS ₂ ) of the return light detection sensor 31. Based on the output 34 (V ₁ , V ₀ ) of the excitation light detection sensor 33, the corrected pulse PLS _AMD is the target pulse PLS for both the temperature state of the laser oscillator 41 and the deterioration state of the semiconductor laser 1. _The drive current D ₁ applied from the drive circuit 2 to the semiconductor laser 1 so as to approach ₁ is corrected to the corrected drive current D _AMD .
Further, according to the present embodiment, not only the effects of the first embodiment and the effect of the second embodiment can be obtained, but also a comparison between the pulse laser return light REF _PLS and the excitation laser reflected light REF _PMP. Therefore, it is possible to detect the connection state between the optical fiber 35 and the laser spark plug 4.

With reference to FIG. 4, the outline of the laser output detection means 3c used in the laser ignition device 100c in the fourth embodiment of the present invention will be described.
In the above-described embodiment, an example in which the beam splitters 30, 30a, and 30b are used as optical elements that split the pulse laser return light REF _PLS or the excitation laser reflected light REF _PMP has been described. However, in this embodiment, a semiconductor is used. The semiconductor laser 1 and the return light detection sensor 31c are used while utilizing a part of the excitation light condensing optical system component 40 that condenses the excitation laser LSR _PMP emitted from the laser 1 as the optical element 30c of the laser output detection means 3c. The laser output detection means 3c is reduced in size by mounting it integrally in a package 36 that seals and protects the semiconductor laser 1 together with the excitation light detection sensor 33c.

In the present embodiment, a plurality of semiconductor lasers 1 are connected in series, and are connected to a positive power supply terminal 200 and a negative power supply terminal 201 drawn to the outside.
One end of the optical fiber 10c is disposed at the emission position of the excitation laser LSR _PMP of each semiconductor laser 1, and the excitation laser LSRPMP is transmitted through the optical fiber 10c.
An optical element 30c is disposed at the other end of the optical fiber 10c. In the optical element 30c, a surface of the side facing the semiconductor laser 1 (input side) is formed with a dereflection film 302c called so-called AR coating that suppresses reflection of the excitation laser LSR _PMP and improves transmission efficiency. A return light reflecting film 301c that reflects the laser pulse return light REF _PLS is formed on the surface (output side) facing the laser oscillator 41 side.
The optical element 30c also serves as a part of an excitation light condensing optical system component that condenses the excitation laser LSR _PMP transmitted through the optical fiber 10c, and is adjusted so that the excitation laser LSR _PMP becomes parallel light. Thus, the light enters the optical fiber 35c.

Further, the laser pulse return light REF _PLS and the excitation laser reflected light REF _PMP leaking from the gap between the optical element 30c and the optical fiber 35c are returned through the light guide portions 311 and 331 made of quartz, BK7, or the like. Light is incident on the detection sensor 31c and the excitation light detection sensor 33c.
The return light detection sensor 31c is connected to a pair of return light output terminals 310 and 311 drawn to the outside.
The excitation light detection sensor 33c is connected to a pair of excitation light output terminals 330 and 331 drawn to the outside.
The package 36 is made of a metal case or a resin member having high thermal conductivity, and constitutes the semiconductor laser 1 and the laser output detector 3c. The optical fibers 10c and 35c, the optical element 30c, the return light detection sensor 31c, and the excitation light detection. The sensor 33c is integrally sealed to prevent damage and contamination of the optical components and to serve as a heat sink for releasing the heat of the semiconductor laser to the outside.
Alternatively, the package 36 is equipped with a cooling device that uses heat-insulating resin to block heat input from the engine and emit semiconductor laser heat.
According to this embodiment, in addition to being able to exhibit the same effects as in the above embodiment, it is possible to further reduce the size of the laser ignition device 100c.

An overview of a laser ignition device 100d according to the fifth embodiment of the present invention will be described with reference to FIG.
In the present embodiment, as in the fourth embodiment, the semiconductor laser 1 and the laser output detector 3c are integrally sealed in the package 36d and placed on the head of the laser spark plug 4d, and the connector A portion 37 is formed, and a pair of power supply terminals 200 and 201, return light output terminals 310 and 311 and excitation light output terminals 330 and 331 are arranged in the connector portion 37, and the drive circuit 2 and the output energy determination means 5 are arranged. Is connectable via a wire harness provided with a connector portion (not shown) fitted to the connector portion 37.
Further, as a cooling mechanism for preventing heat input from the combustion chamber 73 to the semiconductor laser 1 side and exhausting heat generated by the semiconductor laser 1, the package 36d is formed of a metal material having high thermal conductivity, and is disposed inside the package 36d. The semiconductor laser 1 is used as a heat sink by contacting with the disposed semiconductor laser 1, or the periphery of the semiconductor laser 1 not in contact with the heat sink is covered with a heat insulating resin so as to block heat released from the combustion chamber 73. Is desirable.

In addition, the cooling effect of the heat sink can be enhanced by thermally coupling the engine cooling device for cooling the cylinder head 70 and the package 36d provided as a heat sink, and the temperature environment of the laser oscillator 41 can be changed. The fluctuation width of the oscillation pulse of the pulse laser LSR _PLS to be oscillated can be reduced.
In addition, a wavelength lock mechanism such as a narrow band narrowing element (Volume Bragg Gradings VBG) that limits the wavelength of the excitation laser LSR _PMP within a range of −30 to 130 ° C., for example, 808 ± 3 nm is incorporated in the semiconductor laser 1. Also good.
With this configuration, the conductor laser 1 and the laser spark plug 4 are integrated, and the drive circuit 2 and the semiconductor laser 1 can be easily separated, so that the plug can be easily attached and detached. There is no possibility of threatening the safety of the driver or the like due to malfunction during replacement or leakage of laser light.

With reference to FIG. 6, another example of the control method of the laser ignition device 100 of the present invention will be described. In the above embodiment, when the temperature of the laser oscillator 41 rises and the oscillation period becomes long, the application time of the drive current is extended to obtain the corrected drive current D _AMD. In this case, the driving current is increased to obtain the corrected driving current D _AMD .
By increasing the drive current, the operating time of the Q switch can be shortened even when the temperature of the laser oscillator 41 is high, and the corrected pulse number PLS _AMD can be made to coincide with the target pulse number PLS _1. .

With reference to FIG. 7, an example of the control method of the laser ignition device 100 of the present invention will be described. When the ignition signal IGt from ECU7 is transmitted, the laser characteristics determination region, and the target number of pulses PLS _1, is compared with the output pulses PLS ₂ obtained by the detection of the laser pulse return light _{REF PLS} is, the target number of pulses PLS ₁ The drive current is corrected so as to match.
In the present embodiment, when the temperature of the laser oscillator 41 rises, the oscillation period becomes longer, and when the number of pulses PLS _{2 of} the actually oscillated pulse laser LSR _PLS is less than the target number of pulses PLS ₁ , the semiconductor laser By increasing the application time without changing the drive current applied to 1, the corrected pulse number PLS _AMD can be made to coincide with the target pulse number PLS ₁ in the feedback reflection region.

Further, as the laser oscillator deterioration detection means, the actual output pulse number PLS ₂ detected based on the output of the return light detection sensor 31 oscillates from the laser oscillator 41 in response to one ignition signal IGt transmitted from the ECU 7. When the target pulse number PLS ₁ of the power pulse laser LSR _PLS is smaller than the target pulse number PLS ₁ , the output detected again even if the drive current application time is increased or the drive current D _AMD is driven with the corrected drive current increased. Pal number PLS ₂ is at less than the target number of pulses PLS ₁ may also be determined that the deterioration of the laser oscillator 41.

100 laser igniter 1 semiconductor laser 10, 35 optical fiber 2 semiconductor laser drive circuit 20 semiconductor laser drive signal 3 laser output detection means 30 beam splitter 300 optical element 301 return light partial reflection film 31 return light detection means (return light detection sensor)
32 Return light detection signal 33 Excitation light detection means (excitation light detection sensor)
302 Excitation light partial reflection film 34 Excitation light detection signal 4 Laser spark plug 40 Excitation light adjusting optical system component 41 Laser oscillator 410 Excitation light transmission film 411 Fluorescence partial reflection film 412 Laser resonator 413 Supersaturated absorber 414 Reflector 42 Beam extract Panda 43 Condensing lens 44 Protective cover 45 Plug casing 5 Laser output determination means 50 Laser output determination signal 6 Electronic control unit (ECU)
60 Control target value 7 Internal combustion engine 70 Engine head 71 Intake cylinder 711 Intake valve 72 Exhaust cylinder 721 Exhaust cylinder 73 Combustion chamber FP Condensing point PLS ₁ Target pulse number PLS ₂ Return light pulse number PLS ₃ Excitation light pulse number PLS After _AMD correction Number of pulses D ₁ Drive current D Drive current after _AMD correction

JP 2009-278023 A JP 2009-121247 A

Claims (8)

A driving current for driving the excitation light source is applied in accordance with an ignition signal provided in accordance with the operating state of the engine from an electronic control device that controls the engine, and an excitation laser emitted from the excitation light source is provided. In a laser ignition device that oscillates as a pulse laser having a high energy density by a laser oscillator, further increases the energy density by a condensing means, and ignites an air-fuel mixture in a combustion chamber,
As laser output detection means, an optical element that refracts the traveling direction of the return light of the pulse laser oscillated from the laser oscillator and a return light detection sensor that detects the return light of the pulse laser refracted by the optical element are provided. And a laser ignition device. A driving current for driving the excitation light source is applied in accordance with an ignition signal provided in accordance with the operating state of the engine from an electronic control device that controls the engine, and an excitation laser emitted from the excitation light source is provided. In a laser ignition device that oscillates as a pulse laser having a high energy density by a laser oscillator, further increases the energy density by a condensing means, and ignites an air-fuel mixture in a combustion chamber,
As the excitation light source deterioration detecting means, an optical element that refracts the traveling direction of a part of the excitation laser emitted from the excitation light source, and an excitation light detection sensor that detects a part of the excitation laser refracted by the optical element. A laser ignition device comprising: A driving current for driving the excitation light source is applied in accordance with an ignition signal provided in accordance with the operating state of the engine from an electronic control device that controls the engine, and an excitation laser emitted from the excitation light source is provided. In a laser ignition device that oscillates as a pulse laser having a high energy density by a laser oscillator, further increases the energy density by a condensing means, and ignites an air-fuel mixture in a combustion chamber,
As laser output detection means, an optical element that refracts the traveling direction of the return light of the pulse laser oscillated from the laser oscillator and a return light detection sensor that detects the return light of the pulse laser refracted by the optical element are provided. And
As the excitation light source deterioration detecting means, an optical element that refracts the traveling direction of a part of the excitation laser emitted from the excitation light source, and an excitation light detection sensor that detects a part of the excitation laser refracted by the optical element. A laser ignition device comprising: A driving current for driving the excitation light source is applied in accordance with an ignition signal provided in accordance with the operating state of the engine from an electronic control device that controls the engine, and an excitation laser emitted from the excitation light source is provided. A method for controlling a laser ignition device that oscillates as a pulse laser having a high energy density by a laser oscillator, further increases the energy density by a condenser lens, and ignites an air-fuel mixture in a combustion chamber,
As laser output detection means, an optical element for refracting the traveling direction of the return light of the pulse laser oscillated from the laser oscillator and a return light detection sensor for detecting the return light of the pulse laser refracted by the optical element are provided. ,
The actual number of output pulses detected based on the output of the return light detection sensor is larger than the target number of pulses of the pulse laser to be oscillated from the laser oscillator with respect to one ignition signal transmitted from the electronic control unit. A control method for a laser ignition device, characterized in that when it is small, the drive current application time is lengthened or the drive current is increased. A driving current for driving the excitation light source is applied in accordance with an ignition signal provided in accordance with the operating state of the engine from an electronic control device that controls the engine, and an excitation laser emitted from the excitation light source is provided. A method for controlling a laser ignition device that oscillates as a pulse laser having a high energy density by a laser oscillator, further increases the energy density by a condenser lens, and ignites an air-fuel mixture in a combustion chamber,
As the excitation light source deterioration detecting means, an optical element that refracts the traveling direction of a part of the excitation laser emitted from the excitation light source, and an excitation light detection sensor that detects a part of the excitation laser refracted by the optical element. Provided,
When the peak voltage of the output detected by the excitation light detection sensor is lower than the initial peak voltage of the output detected by the excitation light detection sensor in the initial state in advance, the application time of the drive current is lengthened, or A method of controlling a laser ignition device, wherein the drive current is increased. A driving current for driving the excitation light source is applied in accordance with an ignition signal provided in accordance with the operating state of the engine from an electronic control device that controls the engine, and an excitation laser emitted from the excitation light source is provided. A method for controlling a laser ignition device that oscillates as a pulse laser having a high energy density by a laser oscillator, further increases the energy density by a condenser lens, and ignites an air-fuel mixture in a combustion chamber,
As laser oscillator deterioration detection means, an optical element that refracts the traveling direction of the return light of the pulse laser oscillated from the laser oscillator, and a return light detection sensor that detects the return light of the pulse laser refracted by the optical element. Provided,
The actual number of output pulses detected based on the output of the return light detection sensor is larger than the target number of pulses of the pulse laser to be oscillated from the laser oscillator with respect to one ignition signal transmitted from the electronic control unit. When the number of output pulses detected again after increasing the driving current application time or increasing the driving current is less than the target pulse number when the number is small, it is determined that the laser oscillator has deteriorated. A control method of a laser ignition device characterized by the above. A driving current for driving the excitation light source is applied in accordance with an ignition signal provided in accordance with the operating state of the engine from an electronic control device that controls the engine, and an excitation laser emitted from the excitation light source is provided. A method for controlling a laser ignition device that oscillates as a pulse laser having a high energy density by a laser oscillator, further increases the energy density by a condenser lens, and ignites an air-fuel mixture in a combustion chamber,
As laser oscillator deterioration detection means, an optical element that refracts the traveling direction of the return light of the pulse laser oscillated from the laser oscillator, and a return light detection sensor that detects the return light of the pulse laser refracted by the optical element. Provided,
Despite the fact that an excitation laser is output from the excitation light source, when the output of the return light detection sensor is below a predetermined threshold,
A method for controlling a laser ignition device, comprising: determining that the excitation light source and the laser oscillator are not connected, and stopping oscillation of the excitation laser from the excitation light source. A driving current for driving the excitation light source is applied in accordance with an ignition signal provided in accordance with the operating state of the engine from an electronic control device that controls the engine, and an excitation laser emitted from the excitation light source is provided. A method for controlling a laser ignition device that oscillates as a pulse laser having a high energy density by a laser oscillator, further increases the energy density by a condenser lens, and ignites an air-fuel mixture in a combustion chamber,
As the excitation light source deterioration detecting means, an optical element that refracts the traveling direction of a part of the excitation laser emitted from the excitation light source, and an excitation light detection sensor that detects a part of the excitation laser refracted by the optical element. Provided,
When the difference between the peak voltage of the output detected by the excitation light detection sensor and the initial peak voltage of the output detected by the excitation light detection sensor in the initial state exceeds a predetermined threshold, the excitation light source deteriorates. A method for controlling a laser ignition device, characterized in that:

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